NOx Exceedence - NOx Control Monitoring System
The P2BAE code indicates that the engine control module (ECM) has detected that the nitrogen oxide (NOx) emissions from the vehicle have exceeded the allowable threshold for the NOx control monitoring system. This system monitors the performance of the selective catalytic reduction (SCR) system, diesel exhaust fluid (DEF) quality, and other emissions components. The code is typically triggered when the NOx sensor readings are higher than expected, suggesting a malfunction in the SCR system, DEF injection, or NOx sensors themselves.
01. Most Common Causes
- Faulty NOx sensor
- DEF quality or level issue
- SCR catalyst degradation
- DEF injector clogged or malfunctioning
- Exhaust leak upstream of NOx sensor
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Increased fuel consumption
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Inspect DEF level and quality; check for contamination.
Step 3: Test NOx sensor readings using a scan tool.
Step 4: Check for exhaust leaks and inspect SCR system components.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it may cause further damage to the SCR system and lead to reduced performance or limp mode.
How much does it cost to fix?▼
Costs vary; a NOx sensor replacement can be $200-$500, while DEF system repairs may range from $100-$1000 depending on the issue.